This paper discusses the design of a flyback regulator implemented without a dedicated flyback controller integrated circuit (IC). Instead, all aspects of the voltage-mode controller are implemented discretely using a series of timing ICs, logic gates, and comparators. Utilizing a flyback transformer and an optoisolator, galvanic isolation is maintained in the design of a 12V-25V input, 5V/1A output, DC-DC flyback regulator with a constant switching frequency of 100kHz and fixed duty cycle of 0.443. After performing calculations to determine performance parameters, parts are selected to meet design specifications, schematic capture and printed circuit board (PCB) layout are performed, the PCB is fabricated, and its performance is evaluated. Metrics including load regulation, voltage ripple, line regulation, and efficiency are examined. Across the full input range, the averaged output voltage remained within 1% of the target 5V output. Voltage ripple was kept to within 5% of the output voltage across all output currents.

Publication Date


Document Type

Master's Project

Student Type


Degree Name

Electrical Engineering (MS)

Department, Program, or Center

Electrical Engineering (KGCOE)


Mark A. Indovina

Advisor/Committee Member

Ferat Sahin


RIT – Main Campus